1. Field of the Invention
The present invention relates to a touch detection device for detecting touch or proximity of a user's finger or a pen to a detection surface. In addition, the present invention relates to a display device having a function of the touch detection device (touch sensor).
2. Description of the Related Art
In general, a touch detection device is a device for detecting touch or proximity of a user's finger or a pen to a detection surface.
A display device is known in the art, which allows a user to input information instead of typical buttons by overlappingly forming a touch detection device called a touch panel on a display panel and displaying various buttons as an image on a display surface. When such a display device is applied to a small-sized mobile device, it is possible to obtain various advantages such as a large screen, saving space for a manipulation unit, reduction of components because a display and an arrangement of buttons can be integrated together. As such, generally speaking, the “touch panel” refers to a touch detection device having a panel shape combined with a display device.
It is known that three touch detection types of the touch panel include an optical type, a resistive film type, and an electrostatic capacitance type. Meanwhile, in order to associate an electric variation generated by touch or proximity with positional information, a plurality of wiring lines arranged in a matrix shape combined to determine the position are demanded.
The thickness of the entire display device (e.g., a liquid crystal module) increases when the touch panel is mounted. Particularly, when it is employed in a mobile device, a protection layer for preventing scratches on the touch panel is additionally demanded, thereby further increasing the thickness of the liquid crystal module. This is against a miniaturization trend.
In this regard, for example, Japanese Unexamined Patent Application Publication No. 2008-9750 discloses a touch panel conductive film interposed between a viewer's side panel of the liquid crystal display device and a viewer's side polarization plate disposed in the outer surface thereof. Japanese Unexamined Patent Application Publication No. 2008-9750 proposes a liquid crystal display device having an electrostatic capacitance type touch panel using an external surface of the polarization plate as a touch surface between the touch panel conductive film and the external surface of the polarization plate in order to obtain a thin thickness.